Surging protection Vs Opto-electronic isolation
About serial converters, since it’s used to connect M2M. And working condition is usually having a certain interference, to ensure the data stream reliabilityand avoid cross-talk. How to choose properly protection to reduce theinterference according to certain condition?

Surging protection, divert the surging current to ground via shielding of the connector. So, the casing ofyour equipment needs to be grounded. If the surging comes from outdoor, andgrounding condition is well, you could choose this one.

Opto-electronicisolation, using optical coupler, change the Electronic signal to opticalsignal at one end, and then changing back to Electronic signal at another side.So there is not additional ground required. If the interference is coming frompotential difference, nearby heavy load equips, ESD,  you should choose this one.